Breathing and Exchange of Gases
CBSE · Class 11 · Biology
Summary of Breathing and Exchange of Gases for CBSE Class 11 Biology. Key concepts, important points, and chapter overview.
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Overview
Breathing is the exchange of oxygen from the atmosphere with carbon dioxide produced by body cells. Oxygen is used to release energy from food molecules, while carbon dioxide is a harmful waste product that must be removed. The human respiratory system is organised to bring air into the lungs, excha
Key Concepts
Air enters through the nostrils
Air enters through the nostrils, passes through the nasal chamber, pharynx, larynx, trachea, bronchi, bronchioles and finally reaches the alveoli. The
The part from the external nostrils
The part from the external nostrils up to the terminal bronchioles forms the conducting part. It carries air, filters it, humidifies it and brings it
Inspiration occurs when the intra
Inspiration occurs when the intra-pulmonary pressure becomes less than atmospheric pressure. This happens due to contraction of the diaphragm and exte
Tidal volume is about 500 mL
Tidal volume is about 500 mL. Inspiratory reserve volume is 2500 mL to 3000 mL. Expiratory reserve volume is 1000 mL to 1100 mL. Residual volume is 11
Gas exchange occurs by simple diffusion
Gas exchange occurs by simple diffusion based on partial pressure gradients. Atmospheric pO2 is 159 mm Hg and pCO2 is 0.3 mm Hg. In alveoli, pO2 is 10
Learning Objectives
- Understand the main respiratory organs and their functions
- Explain inspiration and expiration using pressure changes
- Describe respiratory volumes and capacities
- Explain gas exchange at the alveoli and tissues
- Understand transport of oxygen and carbon dioxide in blood
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Sources & Official References
- NCERT Official — ncert.nic.in
- CBSE Academic — cbseacademic.nic.in
- CBSE Official — cbse.gov.in
- National Education Policy 2020 — education.gov.in
Content is aligned to the official syllabus. Refer to the board website for the latest curriculum.
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